1. Technical Field
This invention relates to a fixed-star projecting machine for a planetarium which uses a small-diametered projection globe to make it possible to project not only stars with improved image formation but also constellations, marks and constellation pictures.
2. Prior Art
The conventional planetarium apparatus disclosed in U.S. Pat. No. 3,571,954 projects fixed stars by using a combination of single-sleeve type projectors for projecting stars of the first and brighter magnitudes embedded in a globe and a pin hole type projector with many apertures formed on the surface of the globe for projecting other stars.
With this projecting method, however, to improve the images of stars projected by the pin hole type projector, not only is it necessary to enlarge the globe, but also there is a limit to the number of lens type projectors that can be attached to the globe surface and to the number of auxiliary parts such as electrically conductive springs for feeding power to lamps for said projectors. Further, if the globe is reduced in diameter, the images of stars projected by the pin hole type projector will be inferior in image formation to the images of brighter stars projected by the single-sleeve type projectors. Thus, only a very disharmonius pattern of images of stars projected could be formed on the whole heaven, and there is almost no space available for installing the single-sleeve type projectors and their accessories so that the bright stars must be projected by the pin hole type projectors which are inferior in image formation to single-sleeve type projector.